1 /* 2 * include/linux/sunrpc/cache.h 3 * 4 * Generic code for various authentication-related caches 5 * used by sunrpc clients and servers. 6 * 7 * Copyright (C) 2002 Neil Brown <[email protected]> 8 * 9 * Released under terms in GPL version 2. See COPYING. 10 * 11 */ 12 13 #ifndef _LINUX_SUNRPC_CACHE_H_ 14 #define _LINUX_SUNRPC_CACHE_H_ 15 16 #include <linux/slab.h> 17 #include <asm/atomic.h> 18 #include <linux/proc_fs.h> 19 20 /* 21 * Each cache requires: 22 * - A 'struct cache_detail' which contains information specific to the cache 23 * for common code to use. 24 * - An item structure that must contain a "struct cache_head" 25 * - A lookup function defined using DefineCacheLookup 26 * - A 'put' function that can release a cache item. It will only 27 * be called after cache_put has succeed, so there are guarantee 28 * to be no references. 29 * - A function to calculate a hash of an item's key. 30 * 31 * as well as assorted code fragments (e.g. compare keys) and numbers 32 * (e.g. hash size, goal_age, etc). 33 * 34 * Each cache must be registered so that it can be cleaned regularly. 35 * When the cache is unregistered, it is flushed completely. 36 * 37 * Entries have a ref count and a 'hashed' flag which counts the existance 38 * in the hash table. 39 * We only expire entries when refcount is zero. 40 * Existance in the cache is counted the refcount. 41 */ 42 43 /* Every cache item has a common header that is used 44 * for expiring and refreshing entries. 45 * 46 */ 47 struct cache_head { 48 struct cache_head * next; 49 time_t expiry_time; /* After time time, don't use the data */ 50 time_t last_refresh; /* If CACHE_PENDING, this is when upcall 51 * was sent, else this is when update was received 52 */ 53 atomic_t refcnt; 54 unsigned long flags; 55 }; 56 #define CACHE_VALID 0 /* Entry contains valid data */ 57 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */ 58 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/ 59 60 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */ 61 62 struct cache_detail { 63 int hash_size; 64 struct cache_head ** hash_table; 65 rwlock_t hash_lock; 66 67 atomic_t inuse; /* active user-space update or lookup */ 68 69 char *name; 70 void (*cache_put)(struct cache_head *, 71 struct cache_detail*); 72 73 void (*cache_request)(struct cache_detail *cd, 74 struct cache_head *h, 75 char **bpp, int *blen); 76 int (*cache_parse)(struct cache_detail *, 77 char *buf, int len); 78 79 int (*cache_show)(struct seq_file *m, 80 struct cache_detail *cd, 81 struct cache_head *h); 82 83 /* fields below this comment are for internal use 84 * and should not be touched by cache owners 85 */ 86 time_t flush_time; /* flush all cache items with last_refresh 87 * earlier than this */ 88 struct list_head others; 89 time_t nextcheck; 90 int entries; 91 92 /* fields for communication over channel */ 93 struct list_head queue; 94 struct proc_dir_entry *proc_ent; 95 struct proc_dir_entry *flush_ent, *channel_ent, *content_ent; 96 97 atomic_t readers; /* how many time is /chennel open */ 98 time_t last_close; /* if no readers, when did last close */ 99 time_t last_warn; /* when we last warned about no readers */ 100 void (*warn_no_listener)(struct cache_detail *cd); 101 }; 102 103 104 /* this must be embedded in any request structure that 105 * identifies an object that will want a callback on 106 * a cache fill 107 */ 108 struct cache_req { 109 struct cache_deferred_req *(*defer)(struct cache_req *req); 110 }; 111 /* this must be embedded in a deferred_request that is being 112 * delayed awaiting cache-fill 113 */ 114 struct cache_deferred_req { 115 struct list_head hash; /* on hash chain */ 116 struct list_head recent; /* on fifo */ 117 struct cache_head *item; /* cache item we wait on */ 118 time_t recv_time; 119 void *owner; /* we might need to discard all defered requests 120 * owned by someone */ 121 void (*revisit)(struct cache_deferred_req *req, 122 int too_many); 123 }; 124 125 /* 126 * just like a template in C++, this macro does cache lookup 127 * for us. 128 * The function is passed some sort of HANDLE from which a cache_detail 129 * structure can be determined (via SETUP, DETAIL), a template 130 * cache entry (type RTN*), and a "set" flag. Using the HASHFN and the 131 * TEST, the function will try to find a matching cache entry in the cache. 132 * If "set" == 0 : 133 * If an entry is found, it is returned 134 * If no entry is found, a new non-VALID entry is created. 135 * If "set" == 1 and INPLACE == 0 : 136 * If no entry is found a new one is inserted with data from "template" 137 * If a non-CACHE_VALID entry is found, it is updated from template using UPDATE 138 * If a CACHE_VALID entry is found, a new entry is swapped in with data 139 * from "template" 140 * If set == 1, and INPLACE == 1 : 141 * As above, except that if a CACHE_VALID entry is found, we UPDATE in place 142 * instead of swapping in a new entry. 143 * 144 * If the passed handle has the CACHE_NEGATIVE flag set, then UPDATE is not 145 * run but insteead CACHE_NEGATIVE is set in any new item. 146 147 * In any case, the new entry is returned with a reference count. 148 * 149 * 150 * RTN is a struct type for a cache entry 151 * MEMBER is the member of the cache which is cache_head, which must be first 152 * FNAME is the name for the function 153 * ARGS are arguments to function and must contain RTN *item, int set. May 154 * also contain something to be usedby SETUP or DETAIL to find cache_detail. 155 * SETUP locates the cache detail and makes it available as... 156 * DETAIL identifies the cache detail, possibly set up by SETUP 157 * HASHFN returns a hash value of the cache entry "item" 158 * TEST tests if "tmp" matches "item" 159 * INIT copies key information from "item" to "new" 160 * UPDATE copies content information from "item" to "tmp" 161 * INPLACE is true if updates can happen inplace rather than allocating a new structure 162 * 163 * WARNING: any substantial changes to this must be reflected in 164 * net/sunrpc/svcauth.c(auth_domain_lookup) 165 * which is a similar routine that is open-coded. 166 */ 167 #define DefineCacheLookup(RTN,MEMBER,FNAME,ARGS,SETUP,DETAIL,HASHFN,TEST,INIT,UPDATE,INPLACE) \ 168 RTN *FNAME ARGS \ 169 { \ 170 RTN *tmp, *new=NULL; \ 171 struct cache_head **hp, **head; \ 172 SETUP; \ 173 head = &(DETAIL)->hash_table[HASHFN]; \ 174 retry: \ 175 if (set||new) write_lock(&(DETAIL)->hash_lock); \ 176 else read_lock(&(DETAIL)->hash_lock); \ 177 for(hp=head; *hp != NULL; hp = &tmp->MEMBER.next) { \ 178 tmp = container_of(*hp, RTN, MEMBER); \ 179 if (TEST) { /* found a match */ \ 180 \ 181 if (set && !INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags) && !new) \ 182 break; \ 183 \ 184 if (new) \ 185 {INIT;} \ 186 if (set) { \ 187 if (!INPLACE && test_bit(CACHE_VALID, &tmp->MEMBER.flags))\ 188 { /* need to swap in new */ \ 189 RTN *t2; \ 190 \ 191 new->MEMBER.next = tmp->MEMBER.next; \ 192 *hp = &new->MEMBER; \ 193 tmp->MEMBER.next = NULL; \ 194 t2 = tmp; tmp = new; new = t2; \ 195 } \ 196 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ 197 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 198 else { \ 199 UPDATE; \ 200 clear_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 201 } \ 202 } \ 203 cache_get(&tmp->MEMBER); \ 204 if (set||new) write_unlock(&(DETAIL)->hash_lock); \ 205 else read_unlock(&(DETAIL)->hash_lock); \ 206 if (set) \ 207 cache_fresh(DETAIL, &tmp->MEMBER, item->MEMBER.expiry_time); \ 208 if (set && !INPLACE && new) cache_fresh(DETAIL, &new->MEMBER, 0); \ 209 if (new) (DETAIL)->cache_put(&new->MEMBER, DETAIL); \ 210 return tmp; \ 211 } \ 212 } \ 213 /* Didn't find anything */ \ 214 if (new) { \ 215 INIT; \ 216 new->MEMBER.next = *head; \ 217 *head = &new->MEMBER; \ 218 (DETAIL)->entries ++; \ 219 cache_get(&new->MEMBER); \ 220 if (set) { \ 221 tmp = new; \ 222 if (test_bit(CACHE_NEGATIVE, &item->MEMBER.flags)) \ 223 set_bit(CACHE_NEGATIVE, &tmp->MEMBER.flags); \ 224 else {UPDATE;} \ 225 } \ 226 } \ 227 if (set||new) write_unlock(&(DETAIL)->hash_lock); \ 228 else read_unlock(&(DETAIL)->hash_lock); \ 229 if (new && set) \ 230 cache_fresh(DETAIL, &new->MEMBER, item->MEMBER.expiry_time); \ 231 if (new) \ 232 return new; \ 233 new = kmalloc(sizeof(*new), GFP_KERNEL); \ 234 if (new) { \ 235 cache_init(&new->MEMBER); \ 236 goto retry; \ 237 } \ 238 return NULL; \ 239 } 240 241 #define DefineSimpleCacheLookup(STRUCT,INPLACE) \ 242 DefineCacheLookup(struct STRUCT, h, STRUCT##_lookup, (struct STRUCT *item, int set), /*no setup */, \ 243 & STRUCT##_cache, STRUCT##_hash(item), STRUCT##_match(item, tmp),\ 244 STRUCT##_init(new, item), STRUCT##_update(tmp, item),INPLACE) 245 246 #define cache_for_each(pos, detail, index, member) \ 247 for (({read_lock(&(detail)->hash_lock); index = (detail)->hash_size;}) ; \ 248 ({if (index==0)read_unlock(&(detail)->hash_lock); index--;}); \ 249 ) \ 250 for (pos = container_of((detail)->hash_table[index], typeof(*pos), member); \ 251 &pos->member; \ 252 pos = container_of(pos->member.next, typeof(*pos), member)) 253 254 255 256 extern void cache_clean_deferred(void *owner); 257 258 static inline struct cache_head *cache_get(struct cache_head *h) 259 { 260 atomic_inc(&h->refcnt); 261 return h; 262 } 263 264 265 static inline int cache_put(struct cache_head *h, struct cache_detail *cd) 266 { 267 if (atomic_read(&h->refcnt) <= 2 && 268 h->expiry_time < cd->nextcheck) 269 cd->nextcheck = h->expiry_time; 270 return atomic_dec_and_test(&h->refcnt); 271 } 272 273 extern void cache_init(struct cache_head *h); 274 extern void cache_fresh(struct cache_detail *detail, 275 struct cache_head *head, time_t expiry); 276 extern int cache_check(struct cache_detail *detail, 277 struct cache_head *h, struct cache_req *rqstp); 278 extern void cache_flush(void); 279 extern void cache_purge(struct cache_detail *detail); 280 #define NEVER (0x7FFFFFFF) 281 extern void cache_register(struct cache_detail *cd); 282 extern int cache_unregister(struct cache_detail *cd); 283 284 extern void qword_add(char **bpp, int *lp, char *str); 285 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen); 286 extern int qword_get(char **bpp, char *dest, int bufsize); 287 288 static inline int get_int(char **bpp, int *anint) 289 { 290 char buf[50]; 291 char *ep; 292 int rv; 293 int len = qword_get(bpp, buf, 50); 294 if (len < 0) return -EINVAL; 295 if (len ==0) return -ENOENT; 296 rv = simple_strtol(buf, &ep, 0); 297 if (*ep) return -EINVAL; 298 *anint = rv; 299 return 0; 300 } 301 302 static inline time_t get_expiry(char **bpp) 303 { 304 int rv; 305 if (get_int(bpp, &rv)) 306 return 0; 307 if (rv < 0) 308 return 0; 309 return rv; 310 } 311 312 #endif /* _LINUX_SUNRPC_CACHE_H_ */ 313